Birefringent compensator for reflective polarizers
First Claim
1. An optical device for transforming light comprising:
- a layer of cholesteric material, the layer of cholesteric material adapted for transmitting light having a first circular helicity and reflecting light having a second circular helicity;
a quarter-wave plate positioned on a first side of the layer of cholesteric material, the quarter-wave plate having first and second oppositely oriented sides, the quarter-wave plate converting light having the first circular helicity and transmitted by the layer of cholesteric material into linearly polarized light; and
a compensator disposed between the first side of the layer of cholesteric material and the first side of the quarter-wave plate, the compensator including a positively birefringent C-plate layer.
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Accused Products
Abstract
An optical device for transforming light and an associated liquid crystal display is disclosed. The device includes a layer of cholesteric material of the type which transmits light having a first circular helicity and reflects light having a second circular helicity. A quarter-wave plate positioned on a first side of the layer of cholesteric material converts the transmitted light having the first circular helicity into linearly polarized light. A compensator including a positively birefringent C-plate layer is disposed between the layer of cholesteric material and the quarter-wave plate. The compensator reduces undesirable phase effects in the transmitted light introduced by the layer of cholesteric material. The disclosed LCD employs the optical device to increase backlighting efficiency while improving field of view and chromaticity of the display.
78 Citations
17 Claims
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1. An optical device for transforming light comprising:
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a layer of cholesteric material, the layer of cholesteric material adapted for transmitting light having a first circular helicity and reflecting light having a second circular helicity; a quarter-wave plate positioned on a first side of the layer of cholesteric material, the quarter-wave plate having first and second oppositely oriented sides, the quarter-wave plate converting light having the first circular helicity and transmitted by the layer of cholesteric material into linearly polarized light; and a compensator disposed between the first side of the layer of cholesteric material and the first side of the quarter-wave plate, the compensator including a positively birefringent C-plate layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A liquid crystal display comprising:
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a light source which radiates randomly polarized light; a layer of cholesteric material disposed on a first side of the light source and receiving randomly polarized light from the light source, the layer of cholesteric material adapted for transmitting therethrough light having a first circular helicity and reflecting light having a second circular helicity, the layer of cholesteric material introducing a first angle dependent phase delay in the transmitted light; a compensator disposed on a first side of the layer of cholesteric material opposite the light source, the compensator introducing a second angle dependent phase delay in the transmitted light, the second angle dependent phase delay opposite in sign from a sign of the first angle dependent phase delay; a quarter-wave plate disposed on a first side of the compensator opposite the layer of cholesteric material, the quarter-wave plate converting the transmitted light into linearly polarized light; a polarizer disposed on a first side of the quarter-wave plate opposite the compensator, the polarizer transmitting linearly polarized light therethrough; and a liquid crystal matrix disposed on a first side of the polarizer opposite the quarter-wave plate, the liquid crystal matrix receiving linearly polarized light from the polarizer and using the linearly polarized light to display information. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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Specification